export const getDistance = function(lat1,lng1,lat2,lng2){
	lat1= Number(lat1)
	lng1 = Number(lng1)
	lat2 = Number(lat2)
	lng2 = Number(lng2)
	
	let  getRad = function (d)  {
        return d * Math.PI / 180.0;
    }
	var f = getRad((lat1 + lat2)/2);
	var g = getRad((lat1 - lat2)/2);
	var l = getRad((lng1 - lng2)/2); 
	var sg = Math.sin(g);  
	var sl = Math.sin(l);  
	var sf = Math.sin(f);  
	var s,c,w,r,d,h1,h2;  
	var a = 6378137;  
	var fl = 1/298.257;  
	sg = sg*sg;  
	sl = sl*sl;  
	sf = sf*sf;   
	s = sg*(1-sl) + (1-sf)*sl;  
	c = (1-sg)*(1-sl) + sf*sl;  

	w = Math.atan(Math.sqrt(s/c));  
	r = Math.sqrt(s*c)/w;   
	d = 2*w*a;  
	h1 = (3*r -1)/2/c;  
	h2 = (3*r +1)/2/s;  
	return d*(1 + fl*(h1*sf*(1-sg) - h2*(1-sf)*sg));  
	 
}